Noble gas’s days of fixed atomic weight argon
By 
Katrina Krämer2018-06-07T13:25:00
Chemistry’s standardisation body introduces atomic weight interval for argon and updates weights of another 13 elements
Argon’s days of having a fixed atomic weight are gone. For the first time since its discovery in 1894, the noble gas’s weight will be defined by an interval, reflecting how the its isotope composition varies depending on the source. The International Union of Pure and Applied Chemistry (Iupac) also updated the atomic weights of another 13 elements.
Argon has three stable isotopes, but their ratio depends on where the gas comes from.